<!DOCTYPE html>
<html lang="en">
  <head>
      <meta charset="UTF-8">
      <title>背景</title>
      <style type="text/css">
        div{
          width: 200px;
          height: 100px;
          background-color: #ff7d44;
        }
      </style>
  </head>

  <body>
    <div>
      hello world~
    </div>
  </body>
</html>